Tropical Storm ISAAC

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TROPICAL STORM ISAAC DISCUSSION NUMBER 38
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092012
1000 AM CDT THU AUG 30 2012
CENTER FIXES USING SURFACE OBSERVATIONS AND NOAA DOPPLER WEATHER
RADARS INDICATE THAT ISAAC IS MOVING NORTHWESTWARD AT 330/08 KT.
THE FORECAST TACK AND REASONING REMAIN BASICALLY UNCHANGED FROM THE
PREVIOUS ADVISORY. ISAAC AND ITS REMNANTS ARE EXPECTED TO BE
STEERED NORTHWARD AROUND THE WESTERN PORTION OF A SUBTROPICAL RIDGE
THAT IS LOCATED OVER THE SOUTHEASTERN U.S. THROUGH DAY 2...AND THEN
TURN NORTHEASTWARD AND EASTWARD ON DAY 3-5 AS THE SYSTEM MOVES INTO
WEAK MID-LATITUDE WESTERLY FLOW. THE OFFICIAL TRACK FORECAST IS
VERY CLOSE TO THE PREVIOUS ONE...AND LIES CLOSE TO THE LATEST
DYNAMICAL MODEL CONSENSUS.
THE INITIAL INTENSITY HAS BEEN DECREASED TO 35 KT...AND THAT IS IN
SMALL AREA OVER WATER BETWEEN SOUTHEASTERN LOUISIANA AND THE
MISSISSIPPI COAST...AND PERHAPS EXTENDING A FEW MILES INLAND.
ISAAC WILL CONTINUE TO WEAKEN OVER LAND AND IT IS LIKELY TO BECOME A
TROPICAL DEPRESSION BY THIS EVENING...AND BECOME A POST-TROPICAL
REMNANT LOW BY SATURDAY...IF NOT SOONER. THE OFFICIAL INTENSITY
FORECAST IS SIMILAR TO THE PREVIOUS ONE...AND CLOSELY FOLLOWS THE
DECAY-SHIPS STATISTICAL-DYNAMICAL INTENSITY MODEL.
HEAVY RAINFALL AND A SIGNIFICANT FLOOD THREAT WILL CONTINUE TO
SPREAD INLAND ACROSS PORTIONS OF THE CENTRAL UNITED STATES DURING
THE NEXT SEVERAL DAYS. WATER LEVELS ALONG THE NORTHERN GULF COAST
WILL REMAIN ELEVATED THROUGH AT LEAST THIS MORNING. THE THREAT FOR
TORNADOES WITH THIS SYSTEM ALSO APPEARS TO BE INCREASING TODAY.
FORECAST POSITIONS AND MAX WINDS
INIT 30/1500Z 31.7N 92.1W 35 KT 40 MPH...INLAND
12H 31/0000Z 33.0N 92.8W 30 KT 35 MPH...INLAND
24H 31/1200Z 35.0N 93.3W 25 KT 30 MPH...INLAND
36H 01/0000Z 37.0N 93.3W 20 KT 25 MPH...INLAND
48H 01/1200Z 38.4N 92.3W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 02/1200Z 39.4N 89.2W 15 KT 15 MPH...POST-TROP/REMNT LOW
96H 03/1200Z 39.5N 86.0W 15 KT 15 MPH...POST-TROP/REMNT LOW
120H 04/1200Z 39.5N 83.0W 15 KT 15 MPH...POST-TROP/REMNT LOW
$$
FORECASTER STEWART
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